1. Field of the Invention
The present invention relates to a mixing tank for a fuel cell, which recovers water from exhaust gas of the fuel cell and can be utilized however the mixing tank is oriented.
2. Description of the Related Art
In general, a fuel cell is provided with an anode 103, a cathode 105 and an electrolyte film 107 put therebetween as shown in FIG. 1, in which a direct methanol fuel cell is exemplified. FIG. 2 shows an example of a fuel cell system considered to be a general constitution thereof. Fuel (methanol in this case) is supplied to the anode 103 by mean of a pump 111 and gas (generally air) which contains oxidant (generally oxygen) is supplied to the cathode 105 by means of a pump 113. At the anode 103 and the cathode 105 the following reactions progress respectively.
At the anode 103;CH3OH+H2O->CO2+6H++6e−−121.9 kJ/mol   (1)
At the cathode 105;3/2O2+6H++6e−->3H2O+141.95 kJ/mol  (2)
If the protons and the electrons are freely transported between the anode 103 and the cathode 105, net reaction as described below is completed in the fuel cell. Thereby an electric power generation cannot be achieved.CH3OH+3/2O2->CO2+2H2O+20.05 kJ/mol  (3)
However, the electrolyte film 107 has a cation selectivity so that cations (protons in this case) are selectively transported therethrough in preference to anions (electrons in this case). Therefore the electrons are extracted from the fuel cell so that electric power generation is made possible as shown in FIG. 1. In the course of the power generation, carbon dioxide is generated at the anode 103 and water is generated at the cathode 105.
To develop the cation selectivity, it is necessary to humidify the electrolyte film 107 with water. There is a proposed art in which water is admixed to the fuel housed in a fuel tank in advance so as to be supplied to the electrolyte film 107.
Various applications of the fuel cell are proposed and one of them is a power supply of a mobile electronic device. In a case where the fuel cell is applied to the mobile electronic device, the fuel cell and the fuel tank installed in the mobile electronic device are oriented to various orientations. The fuel must be stably supplied to the fuel cell in whatever manner the electronic device is oriented.
A related art is disclosed in Japanese Patent Publication (Examined) No. H04-14473.